Cooling apparatus of internal combustion engine

ABSTRACT

A cooling apparatus of an internal combustion engine according to the invention comprises a first passage formed in the cylinder block, through which the cooling medium flows for cooling between-bores portions, a second passage formed in the cylinder block, through which the cooling medium flows for cooling a bore-surrounding portion, and a cooling medium supplying mechanism for supplying the cooling medium to the first and second passages such that ability of the cooling medium for cooling the between-bore portions, is different from the ability of the cooling medium for cooling the bore-surrounding portion.

BACKGROUND Field

The invention relates to a cooling apparatus of an internal combustion engine for cooling the internal combustion engine by cooling water.

Description of the Related Art

There is known a cooling apparatus of an internal combustion engine for cooling a cylinder head and a cylinder block of the internal combustion engine by cooling water (for example, see JP 62-99616 A). The known cooling apparatus includes cooing water passages formed in the cylinder head and the cylinder block.

The cooling water passage formed in the cylinder head is separated from the cooling water passage formed in the cylinder block. Hereinafter, the cooling water passage formed in the cylinder head will be referred to as “the head water passage”, and the cooling water passage formed in the cylinder block will be referred to as “the block water passage”.

In the field of the engine, friction resistances of movable parts such as pistons of the engine are requested to be decreased. In order to decrease the friction resistances, it is necessary to maintain a temperature of portions of the cylinder block around cylinder bores at a temperature range capable of decreasing the friction resistances.

An amount of heat that between-bores portions (i.e. portions of the cylinder block between the adjacent cylinder bores) is received from combustion in combustion chambers of the engine, is larger than the amount of heat that bore-surrounding portion (i.e. a portion of the cylinder block surrounding the cylinder bores other than the between-bores portions) is received from the combustion in the combustion chambers.

Thus, when the between-bores portions and the bore-surrounding portion are commonly cooled by the cooling water, the temperatures of the between-bores portions are higher than the temperature of the bore-surrounding portion. As a result, temperatures of the between-bores portions and a temperature of the bore-surrounding portion are not maintained in the temperature range capable of decreasing the friction resistances.

SUMMARY

The invention has been made for solving the above-mentioned problems. An object of the invention is to provide a cooling apparatus of the internal combustion engine for maintaining the temperatures of the between-bores portions and the bore-surrounding portion in the temperature range capable of decreasing the friction resistances.

A cooling apparatus of an internal combustion engine (10) according to the invention cools a cylinder block (30) of the internal combustion engine and a cylinder head (20) mounted on the cylinder block by cooling medium. Cylinder bores (31 to 33) are formed in the cylinder block.

The cooling apparatus according to the invention comprises a first passage (52 and 53), a second passage (50) and a cooling medium supplying mechanism (60 to 62, 71 to 77, and 90; and 63 to 66, 72 to 74, 78, and 79).

The first passage is formed in the cylinder block, through which the cooling medium flows for cooling between-bores portions (30L and 30R) each corresponding to a portion of the cylinder block surrounding and between adjacent cylinder bores formed in the cylinder block.

The second passage is formed in the cylinder block, through which the cooling medium flows for cooling a bore-surrounding portion (30P) corresponding to a portion of the cylinder block surrounding the cylinder bores other than the between-bores portions.

The cooling medium supplying mechanism may supply the cooling medium to the first and second passages such that ability of the cooling medium for cooling the between-bore portions, is different from the ability of the cooling medium for cooling the bore-surrounding portion.

The cooling apparatus according to the invention may supply the cooling medium to the first passage, through which the cooling medium flows to cool the between-bores portions, and the second passage, through which the cooling medium flows to cool the bore-surrounding portion such that ability of the cooling medium of cooling the between-bores portions, is different from ability of the cooling medium of cooling the bore-surrounding portion by the cooling medium supplying mechanism. Therefore, the cooling apparatus according to the invention may supply the cooling medium having the relatively large ability of cooling the between-bores portions and the cooling medium having the relatively large ability of cooling the bore-surrounding portion. Thus, the temperatures of the between-bores portions and the bore surrounding portion may be maintained in the temperature range capable of decreasing the friction resistances.

The cm supplying mechanism may include a head passage (40) formed in the cylinder head, through which the cooling medium flows for cooling the cylinder head. In this case, the first passage may be connected to the head passage.

It is desired to maintain the temperature of the cylinder head at a low temperature for preventing knocking from being generated in the engine. When the first passage is communicated with the head passage, the temperatures of the between-bores portions is likely to be maintained in the temperature range capable of decreasing the friction resistances by supplying to the head passage the cooling medium having the ability of cooling the cylinder head to maintain the temperature of the cylinder head to a temperature range capable of preventing the generation of the knocking in the engine. Therefore, according to the invention, even though the cooling apparatus has a simple configuration, the temperatures of the between-bores portions may be maintained in the temperature range capable of decreasing the friction resistances.

The cm supplying mechanism may include a common passage (71) communicated with the first and second passages and a flow rate control valve (62) for controlling a flow rate of the cooling medium supplied to the second passage via the common passage.

As the flow rate of the cooling medium supplied to the second passage decreases, a degree of cooling the bore-surrounding portion by the cooling medium decreases. On the other hand, as the flow rate of the cooling medium supplied to the second passage increases, a degree of cooling the between-bores portions by the cooling medium increases. When the flow rate of the cooling medium supplied to the second passage is decreased by the flow rate control valve while the cooling medium is supplied to the first and second passage via the common passage, the flow rate of the cooling medium supplied to the first passage increases. Therefore, the degree of cooling the bore-surrounding portion by the cooling medium supplied to the second passage changes by changing the flow rate of the cooling medium supplied to the second passage. Similarly, the degree of cooling the between-bores portions by the cooling medium supplied to the first passage changes by changing the flow rate of the cooling medium supplied to the first passage.

Therefore, the cooling medium having the ability of cooling the between-bores portions to maintain the temperatures of the between-bores portions in the temperature range capable of decreasing the friction resistances, may be surely supplied to the first passage, and the cooling medium having the ability of cooling the bore-surrounding portion to maintain the temperatures of the bore-surrounding portion in the temperature range capable of decreasing the friction resistances, may be surely supplied to the second passage by adjusting the flow rate of the cooling medium supplied to the second passage by the flow rate control valve. Thus, the temperatures of the between-bores portions and the bore-surrounding portion may be maintained surely in the temperature range of decreasing the friction resistances.

The cm supplying mechanism may include a first cooling device (64) for cooling the cooling medium supplied to the first passage and a second cooling device (66) for cooling the cooling medium supplied to the second passage. In this case, ability of the first cooling device of cooling the cooling medium may be larger than the ability of the second cooling device of cooling the cooling medium.

According to the invention, the first cooling device for cooling the cooling medium supplied to the first passage and the second cooling device for cooling the cooling medium supplied to the second passage, are provided separately. Therefore, the cooling medium having the ability of cooling the between-bores portions to maintain the temperatures of the between-bores portions in the temperature range capable of decreasing the friction resistances, may be supplied to the first passage by setting the ability of the first cooling device of cooling the cooling medium such that the cooling medium having the temperature capable of maintaining the temperatures of the between-bores portions in the temperature range of decreasing the friction resistances, is supplied to the first passage. On the other hand, the cooling medium having the ability of cooling the bore-surrounding portion to maintain the temperature of the bore-surrounding portions in the temperature range capable of decreasing the friction resistances, is supplied to the second passage by setting the ability of the second cooling device of cooling the cooling medium such that the cooling medium having the temperature capable of maintaining the temperature of the bore-surrounding portion in the temperature range of decreasing the friction resistances, is supplied to the second passage. Thus, the temperatures of the between-bores portions and the bore-surrounding portion may be maintained surely in the temperature range of decreasing the friction resistances.

In the above description, for facilitating understanding of the present invention, elements of the present invention corresponding to elements of an embodiment described later are denoted by reference symbols used in the description of the embodiment accompanied with parentheses. However, the elements of the present invention are not limited to the elements of the embodiment defined by the reference symbols. The other objects, features, and accompanied advantages of the present invention can be easily understood from the description of the embodiment of the present invention along with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a view for showing a cooling apparatus according to an embodiment of the invention and an internal combustion engine, to which the cooling apparatus is applied.

FIG. 1B is a view for showing a cylinder head shown in FIG. 1A.

FIG. 1C is a view for showing a cylinder block shown in FIG. 1A.

FIG. 2A is a cross sectional view for showing the cylinder head along a plane P21 shown in FIG. 1B in a direction of an arrow A21.

FIG. 2B is a cross sectional view for showing the cylinder head along a plane Psp shown in FIG. 2A in a direction of an arrow A22.

FIG. 2C is a cross sectional view for showing the cylinder head along a plane P23 shown in FIG. 2A in a direction of an arrow A23.

FIG. 2D is a cross sectional view for showing the cylinder head along a plane P24 shown in FIG. 2A in a direction of an arrow A24.

FIG. 3A is a cross sectional view for showing the cylinder head along a plane P31 shown in FIG. 2A in a direction of an arrow A31.

FIG. 3B is a cross sectional view for showing the cylinder head along a plane P32 shown in FIG. 2A in a direction of an arrow A32.

FIG. 3C is a cross sectional view for showing the cylinder head along a plane P33 shown in FIG. 2A in a direction of an arrow A33.

FIG. 4A is a cross sectional view for showing the cylinder block along a plane P41 shown in FIG. 1C in a direction of an arrow A41.

FIG. 4B is a cross sectional view for showing the cylinder block along a plane Pb shown in FIG. 4A in a direction of an arrow A42.

FIG. 4C is a cross sectional view for showing the cylinder block along a plane P43 shown in FIG. 4A in a direction of an arrow A43.

FIG. 5 is a plane view for showing the cylinder block in a direction of the arrow A41 shown in FIG. 1C.

FIG. 6A is a cross sectional view for showing the cylinder block along a plane P61 shown in FIG. 5 in a direction of an arrow A61.

FIG. 6B is a cross sectional view for showing the cylinder block along a plane P62 shown in FIG. 5 in a direction of an arrow A62.

FIG. 6C is a cross sectional view for showing the cylinder block along a plane P63 shown in FIG. 5 in a direction of an arrow A63.

FIG. 7 is a view for showing a cooling water circulation route of the cooling apparatus according to the embodiment.

FIG. 8 is a view similar to FIG. 7 for describing an operation of the cooling apparatus shown in FIG. 7.

FIG. 9 is a view for showing the cooling water circulation route of the cooling apparatus according to a modified example of the embodiment.

FIG. 10A is a view for showing a part of the cooling water circulation route, which the cooling apparatuses according to the embodiment and the modified example may employ.

FIG. 10B is a view for showing a part of another cooling water circulation route, which the cooling apparatuses according to the embodiment and the modified example may employ.

FIG. 11A is a view for showing a part of further another cooling water circulation route, which the cooling apparatuses according to the embodiment and the modified example may employ.

FIG. 11B is a view for showing a part of further another cooling water circulation route, which the cooling apparatuses according to the embodiment and the modified example may employ.

FIG. 12A is a view for showing a part of further another cooling water circulation route, which the cooling apparatuses according to the embodiment and the modified example may employ.

FIG. 12B is a view for showing a part of further another cooling water circulation route, which the cooling apparatuses according to the embodiment and the modified example may employ.

FIG. 13A is a view for showing a part of further another cooling water circulation route, which the cooling apparatuses according to the embodiment and the modified example may employ.

FIG. 13B is a view for showing a part of further another cooling water circulation route, which the cooling apparatuses according to the embodiment and the modified example may employ.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A cooling apparatus of an internal combustion engine according to an embodiment of the invention, will be described with reference to the drawings. As shown in FIG. 1A, an internal combustion engine 10, to which the cooling apparatus according to the embodiment, includes a cylinder head 20 and a cylinder block 30. The cylinder head 20 is mounted on the cylinder block 30 and secured to the cylinder block 30 by securing devices such as bolts.

The cylinder head 20 has actually a complicated shape. In this embodiment, for simplifying the description, the cylinder head 20 has a rectangular parallelepiped shape as shown in FIG. 1A and FIG. 1B. Similarly, the cylinder block 30 has actually a complicated shape. In this embodiment, for simplifying the description, the cylinder block 30 has a rectangular parallelepiped shape as shown in FIG. 1A and FIG. 1C.

In this description, a block contact surface 20B of the cylinder head 20 is a wall surface of the cylinder head 20 contacting the cylinder block 30 when the cylinder head 20 is mounted on the cylinder block 30. A head contact surface 30H of the cylinder block 30 is a wall surface of the cylinder block 30 contacting the cylinder head 20 when the cylinder head 20 is mounted on the cylinder block 30.

As shown in FIG. 2A to FIG. 2D, three head spaces 21 to 23 are provided on the block contact surface 20B of the cylinder head 20. Each of the head spaces 21 to 23 has a generally-conical shape. The head spaces 21 to 23 are provided such that center axes C21 to C23 are on a same plane.

Hereinafter, one of the head spaces 21 and 23 provided at an outer side (i.e., the head space 21 provided at a left side of FIG. 2A) will be referred to as “the left head space 21”. The remaining head space 23 provided at an inner side will be referred to as “the right head space 23”. The head space 22 provided between the left and right head spaces 21 and 23, will be referred to as “the center head space 22”.

One head water passage 40 and six communication water passage 41 to 46 are formed in the cylinder head 20. Each of the head water passage 40 and the communication water passages 41 to 46 is a water passage, through which cooling medium such as cooling water flows.

The head water passage 40 includes an inlet 40in and an outlet 40out. The cooling water flows into the head water passage 40 via the inlet 40in. The cooling water flows out from the head water passage 40 via the outlet 40out. The head water passage 40 is mainly provided in a portion of the cylinder head 20 surrounding the head spaces 21 to 23.

As shown in FIG. 2A to FIG. 2D, and FIG. 3A to FIG. 3C, each of the communication water passages 41 to 46 has a circular cross section. Each of the communication water passages 41 to 46 are provided such that each of the communication water passages 41 to 46 extends from the head water passage 40 to the block contact surface 20B of the cylinder head 20 in a direction parallel with the center axes C21 to C23 of the head spaces 21 to 23.

Each of the communication water passages 41 and 42 is provided such that a center axis of each of the communication water passages 41 and 42 is on a plane P31 perpendicular to a plane Psp including the center axes C21 to C23 of the head spaces 21 to 23. Each of the communication water passages 43 and 44 is provided such that a center axis of each of the communication water passages 43 and 44 is on a plane P32 perpendicular to the plane Psp. Each of the communication water passages 45 and 46 is provided such that a center axis of each of the communication water passages 45 and 46 is on a plane P33 perpendicular to the plane Psp.

Each of the communication water passages 41, 43 and 45 is provided such that the center axis of each of the communication water passages 41, 43 and 45 is on a plane P23 parallel with the plane Psp and away from the plane Psp at one side (upper side of FIG. 2A) by a predetermined distance D. Each of the communication water passages 42, 44 and 46 is provided such that the center axis of each of the communication water passages 42, 44 and 46 is on a plane P24 parallel with the plane Psp and away from the plane Psp at the other side (lower side of FIG. 2A) by the predetermined distance D.

As shown in FIG. 4A to FIG. 4C, three cylinder bores 31 to 33 are provided in the cylinder block 30. Each of the cylinder bores 31 to 33 has a cylindrical space. Each of the cylinder bores 31 to 33 is provided such that center axes C31 to C33 of the cylinder bores 31 to 33 are on the same plane Pb. Hereinafter, the plane Pb will be referred to as “the bore axis plane Pb”.

Hereinafter, one of the cylinder bores 31 and 33 provided at an outer side (i.e., the left cylinder bore 31 provided at a left side of FIG. 4A) will be referred to as “the left cylinder bore 31”. The remaining cylinder bore 33 provided at an inner side (i.e., the right cylinder bore 33 provided at a right side of FIG. 4A) will be referred to as “the right cylinder bore 33”. The cylinder bore 32 provided between the left and right cylinder bores 31 and 33, will be referred to as “the center cylinder bore 32”.

The left cylinder bore 31 is provided such that a center axis C31 of the left cylinder bore 31 corresponds to the center axis C21 of the left head space 21 in the state that the cylinder head 20 is mounted on the cylinder block 30. The center cylinder bore 32 is provided such that a center axis C32 of the center cylinder bore 32 corresponds to the center axis C22 of the center head space 22 in the state that the cylinder head 20 is mounted on the cylinder block 30. The right cylinder bore 33 is provided such that a center axis C33 of the right cylinder bore 33 corresponds to the center axis C23 of the right head space 23 in the state that the cylinder head 20 is mounted on the cylinder block 30.

One bore-surrounding water passage 50, one bore-side water passage 51, and two between-bores water passage 52 and 53 are provided in the cylinder block 30. Each of the bore-surrounding water passage 50, the bore-side water passage 51, and the between-bores water passage 52 and 53 is a water passage, which through the cooling medium such as the cooling water flows.

The bore-surrounding water passage 50 includes an inlet 50in and an outlet 50out. The cooling water flows into the bore-surrounding water passage 50 via the inlet 50in. The cooling water flows out from the bore-surrounding water passage 50 via the outlet 50out. As shown in FIG. 4A, the bore-surrounding water passage 50 is provided in a bore-surrounding portion 30P which is a portion of the cylinder block 30 surrounding the bores 31 to 33 other than a bore-side portion 30S, a left between-bores portion 30L, and a right between-bores portion 30R of the cylinder block 30.

The bore-side portion 30S is a portion of the cylinder block 30 between the left cylinder bore 31 and a left wall surface 30W of the cylinder block 30. The left between-bores portion 30L is a portion of the cylinder block 30 between the left and center cylinder bores 31 and 32. The right between-bores portion 30R is a portion of the cylinder block 30 between the center and right cylinder bores 32 and 33.

The bore-side water passage 51 is provided in the bore-side portion 30S. As shown in FIG. 5, the bore-side water passage 51 includes an inlet 51in having a circular section and an outlet 51out having a circular section. The cooling water flows into the bore-side water passage 51 via the inlet 51in. The cooling water flows out from the bore-side water passage 51 via the outlet 51out. As shown in FIG. 6A, the inlet 51in and the outlet 51out of the bore-side water passage 51 open at the head contact surface 30H of the cylinder block 30.

The between-bores water passage 52 is provided in the left between-bores portion 30L. Hereinafter, the between-bores water passage 52 will be referred to as “the left between-bores water passage 52”. As shown in FIG. 5, the left between-bores water passage 52 includes an inlet 52in having a circular section and an outlet 52out having a circular section. The cooling water flows into the left between-bores water passage 52 via the inlet 52in. The cooling water flows out from the left between-bores water passage 52 via the outlet 52out. As shown in FIG. 6B, the inlet 52in and the outlet 52out of the left between-bores water passage 52 open at the head contact surface 30H of the cylinder block 30.

The between-bores water passage 53 is provided in the right between-bores portion 30R. Hereinafter, the between-bores water passage 53 will be referred to as “the right between-bores water passage 53”. As shown in FIG. 5, the right between-bores water passage 53 includes an inlet 53in having a circular section and an outlet 53out having a circular section. The cooling water flows into the right between-bores water passage 53 via the inlet 53in. The cooling water flows out from the right between-bores water passage 53 via the outlet 53out. As shown in FIG. 6C, the inlet 53in and the outlet 53out of the right between-bores water passage 53 open at the head contact surface 30H of the cylinder block 30.

As shown in FIG. 5, the inlet 51in and the outlet 51out of the bore-side water passage 51 are provided such that centers of the inlet 51in and the outlet 51out are on a plane P61 perpendicular to the bore axis plane Pb including the center axes C31 to C33 of the left cylinder bore 31 to 33. The inlet 52in and the outlet 52out of the left between-bores water passage 52 are provided such that centers of the inlet 52in and the outlet 52out are on a plane P62 perpendicular to the bore axis plane Pb. The inlet 53in and the outlet 53out of the right between-bores water passage 53 are provided such that centers of the inlet 53in and the outlet 53out are on a plane P63 perpendicular to the bore axis plane Pb.

The inlet 51in of the bore-side water passage 51, the inlet 52in of the left between-bores water passage 52, and the inlet 53in of the right between-bores water passage 53 are provided such that the centers of the inlets 51in, 52in, and 53in are on a plane 64P parallel with the bore axis plane Pb and away from the bore axis plane Pb toward one side (upper side of FIG. 5) by the predetermined distance D.

The outlet 51out of the bore-side water passage 51, the outlet 52out of the left between-bores water passage 52, and the outlet 53out of the right between-bores water passage 53 are provided such that the centers of the outlets 51out, 52out, and 53out are on a plane 65P parallel with the bore axis plane Pb and away from the bore axis plane Pb toward the other side (lower side of FIG. 5) by the predetermined distance D.

The inlet 51in of the bore-side water passage 51 is provided at a position that the inlet 51in communicates with the head water passage 40 via the communication water passage 41 of the cylinder head 20 in the state that the cylinder head 20 is mounted on the cylinder block 30. The outlet 51out of the bore-side water passage 51 is provided at a position that the outlet 51out communicates with the head water passage 40 via the communication water passage 42 of the cylinder head 20 in the state that the cylinder head 20 is mounted on the cylinder block 30.

The inlet 52in of the left between-bores water passage 52 is provided at a position that the inlet 52in communicates with the head water passage 40 via the communication water passage 43 of the cylinder head 20 in the state that the cylinder head 20 is mounted on the cylinder block 30. The outlet 52out of the left between-bores water passage 52 is provided at a position that the outlet 52out communicates with the head water passage 40 via the communication water passage 44 of the cylinder head 20 in the state that the cylinder head 20 is mounted on the cylinder block 30.

The inlet 53in of the right between-bores water passage 53 is provided at a position that the inlet 53in communicates with the head water passage 40 via the communication water passage 45 of the cylinder head 20 in the state that the cylinder head 20 is mounted on the cylinder block 30. The outlet 53out of the right between-bores water passage 53 is provided at a position that the outlet 53out communicates with the head water passage 40 via the communication water passage 46 of the cylinder head 20 in the state that the cylinder head 20 is mounted on the cylinder block 30.

As shown in FIG. 6A, the bore-side water passage 51 extends along the plane P61 (see FIG. 5) from the inlet 51in to the bore axis plane Pb obliquely to the bore axis plane Pb. The bore-side water passage 51 changes its extension direction at the bore axis plane Pb and extends along the plane P61 from the bore axis plane Pb to the outlet 51out obliquely to the bore axis plane Pb.

As shown in FIG. 6B, the left between-bores water passage 52 extends along the plane P62 (see FIG. 5) from the inlet 52in to the bore axis plane Pb obliquely to the bore axis plane Pb. The left between-bores water passage 52 changes its extension direction at the bore axis plane Pb and extends along the plane P62 from the bore axis plane Pb to the outlet 52out obliquely to the bore axis plane Pb.

As shown in FIG. 6C, the right between-bores water passage 53 extends along the plane P63 (see FIG. 5) from the inlet 53in to the bore axis plane Pb obliquely to the bore axis plane Pb. The right between-bores water passage 53 changes its extension direction at the bore axis plane Pb and extends along the plane P63 from the bore axis plane Pb to the outlet 53out obliquely to the bore axis plane Pb.

As shown in FIG. 7, the cooling apparatus according to the embodiment includes a pump 60, a radiator 61, and a flow rate control valve 62.

The pump 60 is activated by rotation of a crank shaft (not shown) of the engine 10. One end 71A of a common water supply pipe 71 is connected to a discharging opening 60out of the pump 60. The common water supply pipe 71 defines a cooling water passage, through which the cooling water flows.

The other end 71B of the common water supply pipe 71 is connected to one end 72A of a head water supply pipe 72 and one end 73A of a block water supply pipe 73. Each of the head and block water supply pipes 72 and 73 defines the cooling water passage. The other end 72B of the head water supply pipe 72 is connected to the inlet 40in of the head water passage 40. The other end 73B of the block water supply pipe 73 is connected to the inlet 50in of the bore-surrounding water passage 50.

The outlet 40out of the head water passage 40 is connected to one end 74A of a head discharging pipe 74 defining the cooling water passage. A temperature sensor 91 is provided on the head discharging pipe 74. The temperature sensor 91 is electrically connected to an electronic control unit 90. The temperature sensor 91 detects a temperature THWhd of the cooling water flowing through the head discharging pipe 74 and outputs a signal representing the temperature THWhd to the electronic control unit 90. The electronic control unit 90 acquires the temperature THWhd on the basis of the signal. Hereinafter, the electronic control unit 90 will be referred to as “the ECU 90”. The temperature THWhd will be referred to as “the head water temperature THWhd”.

The outlet 50out of the bore-surrounding water passage 50 is connected to one end 75A of a block discharging pipe 75 defining the cooling water passage. A temperature sensor 92 is provided on the block discharging pipe 75. The temperature sensor 92 is electrically connected to the ECU 90. The temperature sensor 92 detects a temperature THWbr of the cooling water flowing through the block discharging pipe 75 and outputs a signal representing the temperature THWbr to the ECU 90. The ECU 90 acquires the temperature THWbr on the basis of the signal. Hereinafter, the temperature THWbr will be referred to as “the block water temperature THWbr”.

The other end 74B of the head discharging pipe 74 and the other end 75B of the block discharging pipe 75 are connected to one end 76A of a common discharging pipe 76 defining the cooling water passage. The other end 76B of the common discharging pipe 76 is connected to an inlet 61in of the radiator 61. An outlet 61out of the radiator 61 is connected to one end 77A of a common return pipe 77 defining the cooling water passage. The other end 77B of the common return pipe 77 is connected to a suctioning opening 60in of the pump 60. The radiator 61 is a cooling device for cooling the cooling water flowing through the radiator 61.

The flow rate control valve 62 is provided in the block water supply pipe 73. The flow rate control valve 62 is electrically connected to the ECU 90. An opening degree of the flow rate control valve 62 is controlled by the ECU 90. When the opening degree of the flow rate control valve 62 is controlled to zero, that is, when the flow rate control valve 62 is closed, the cooling water passage defined by the block water supply pipe 73 is shut off by the flow rate control valve 62. In this case, the flow rate of the cooling water flowing through the flow rate control valve 62 is zero.

When the opening degree of the flow rate control valve 62 increases while a discharging flow rate of the cooling water from the pump 60 is constant, the flow rate of the cooling water flowing through the flow rate control valve 62 increases. When the opening degree of the flow rate control valve 62 is controlled to a maximum opening degree, that is, when the radiator 61 opens fully, the flow rate of the cooling water flowing through the flow rate control valve 62 is controlled to a maximum flow rate associated with the flow rate of the cooling water discharged from the pump 60.

The ECU 90 is an electronic control circuit including a microcomputer as a main component including a CPU, a ROM, a RAM, an interface, etc. The CPU realizes various functions by executing instructions or routines stored in a memory (i.e., the ROM).

An acceleration pedal operation amount sensor 93 and a crank angle sensor 94 are electrically connected to the ECU 90.

The acceleration pedal operation amount sensor 93 detects an operation amount AP of an acceleration pedal (not shown) and outputs a signal representing the operation amount AP. The ECU 90 acquires an engine load KL requested for the engine 10 on the basis of the signal.

The crank angle sensor 94 outputs a pulse signal to the ECU 90 every the crank shaft (not shown) rotates by a predetermined angle. The ECU 90 acquires a rotation speed of the engine 10 as an engine speed NE on the basis of the pulse signal.

<Operation of Cooling Apparatus>

Below, an operation of the cooling apparatus according to the embodiment will be described. The pump 60 is activated while the engine 10 operates. Thereby, as shown in FIG. 8, the cooling water is discharged to the common water supply pipe 71 via the discharging opening 60out of the pump 60.

When the opening degree of the flow rate control valve 62 is larger than zero, a part of the cooling water flowing out from the common water supply pipe 71, flows into the head water supply pipe 72, and the remaining of the cooling water flowing out from the common water supply pipe 71, flows into the block water supply pipe 73. As the opening degree of the flow rate control valve 62 increases, the flow rate of the cooling water flowing into the block water supply pipe 73, increases. As a result, the flow rate of the cooling water flowing into the head water supply pipe 72, decreases.

On the other hand, when the opening degree of the flow rate control valve 62 is zero, no cooling water flows into the block water supply pipe 73. Therefore, all of the cooling water flowing out from the common water supply pipe 71, flows into the head water supply pipe 72.

The ECU 90 sets a target of the opening degree of the flow rate control valve 62 on the basis of the engine load KL, the engine speed NE, the head water temperature THWhd, the block water temperature THWbr, etc. In particular, the ECU 90 sets the target of the opening degree of the flow rate control valve 62 such that the cooling water having the flow rate capable of accomplishing a request for preventing knocking from being generated in cylinders of the engine 10, flows into the head water passage 40, and the cooling water having the flow rate capable of accomplishing a request for decreasing friction, flows into the bore-surrounding water passage 50. The ECU 90 controls the opening degree of the flow rate control valve 62 to the target of the opening degree of the flow rate control valve 62. Hereinafter, the request for preventing the knocking from being generated in the cylinders of the engine 10, will be referred to “the knocking prevention request”. The request for decreasing the friction will be referred to as “the friction decreasing request”.

The cooling water flowing out from the head water supply pipe 72, flows into the head water passage 40 via the inlet 40in. A part of the cooling water flowing into the head water passage 40, flows into the bore-side water passage 51, the left between-bores water passage 52, and the right between-bores water passage 53 through the communication water passages 41, 43, and 45, respectively. Therefore, the communication water passages 41, 43, and 45 are water passages for connecting the bore-side water passage 51, the left between-bores water passage 52, and the right between-bores water passage 53 to the head water passage 40, respectively.

The cooling water flowing out from the bore-side water passage 51, the left between-bores water passage 52, and the right between-bores water passage 53, returns to the head water passage 40 through the communication water passages 42, 44, and 46, respectively. Therefore, the communication water passages 42, 44, and 46 are water passages for connecting the bore-side water passage 51, the left between-bores water passage 52, and the right between-bores water passage 53 to the head water passage 40, respectively.

The bore-side portion 30S is cooled by the cooling water flowing through the bore-side water passage 51. The left between-bores portion 30L is cooled by the cooling water flowing through the left between-bores water passage 52. The right between-bores portion 30R is cooled by the cooling water flowing through the right between-bores water passage 53. Therefore, the bore-side water passage 51 is a water passage provided in the cylinder block 30, through which the cooling water for cooling the bore-side portion 30S flows. The left between-bores water passage 52 is a water passage provided in the cylinder block 30, through which the cooling water for cooling the left between-bores portion 30L flows. The right between-bores water passage 53 is a water passage provided in the cylinder block 30, through which the cooling water for cooling the right between-bores portion 30R flows.

The cooling water returned to the head water passage 40, is discharged to the head discharging pipe 74 via the outlet 40out.

The remaining of the cooling water flowing into the head water passage 40, flows through the head water passage 40 and is discharged to the head discharging pipe 74 via the outlet 40out. The cylinder head 20 is cooled by the cooling water flowing through the head water passage 40. Therefore, the head water passage 40 is a water passage provided in the cylinder head 20, through which the cooling water for cooling the cylinder head 20 flows.

On the other hand, the cooling water flowing out from the block water supply pipe 73, flows into the bore-surrounding water passage 50 via the inlet 50in. The cooling water flowing into the bore-surrounding water passage 50, flows through the bore-surrounding water passage 50 and is discharged to the block discharging pipe 75 via the outlet 50out. The bore-surrounding portion 30P is cooled by the cooling water flowing through the bore-surrounding water passage 50. Therefore, the bore-surrounding water passage 50 is a water passage provided in the cylinder block 30, through which the cooling water for cooling the bore-surrounding portion 30P flows.

The flow rate of the cooling water flowing into the bore-surrounding water passage 50, is controlled by the flow rate control valve 62. Therefore, the flow rate control valve 62 is a device for controlling the flow rate of the cooling water supplied to the bore-surrounding water passage 50 through the common water supply pipe 71, that is, controlling a degree of cooling the bore-surrounding portion 30P by the cooling water supplied to the bore-surrounding water passage 50.

The cooling water flowing out from the head and block discharging pipes 74 and 75, flows into the common discharging pipe 76. The cooling water flowing out from the common discharging pipe 76, flows into the radiator 61. The cooling water is cooled by the radiator 61 while the cooling water flows through the radiator 61. The cooling water flowing out from the radiator 61, flows into the common return pipe 77. The cooling water flowing out from the common return pipe 77, is suctioned into the pump 60 via the suctioning opening 60in.

According to the embodiment, the flow rate of the cooling water flowing into the left between-bores water passage 52 and the right between-bores water passage 53 through the head water passage 40 and the flow rate of the cooling water flowing into the bore-surrounding water passage 50 may be controlled independently by controlling and adjusting the opening degree of the flow rate control valve 62.

Therefore, the temperatures of the left between-bores portion 30L, the right between-bores portion 30R, and the bore-surrounding portion 30P may be maintained in a friction decreasing temperature range described below by controlling the opening degree of the flow rate control valve 62 such that the flow rate of the cooling water supplied to the head water passage 40 is controlled to a flow rate capable of maintaining the temperature of the cylinder head 20 in a knocking prevention temperature range described below and maintaining the temperatures of the left between-bores portion 30L and the right between-bores portion 30R in the friction decreasing temperature range, and the flow rate of the cooling water supplied to the bore-surrounding water passage 50 is controlled to a flow rate capable of maintaining the temperature of the bore-surrounding portion 30P in the friction decreasing temperature range. The friction decreasing temperature range is a temperature range capable of accomplishing the friction decreasing request. The knocking prevention temperature range is a temperature range capable of accomplishing the knocking prevention request.

It should be noted that the present invention is not limited to the aforementioned embodiment, and various modifications can be employed within the scope of the present invention.

Modified Example

As shown in FIG. 9, the cooling apparatus according to a modified example of the embodiment may be configured such that a cooling water circulation route for supplying the cooling water to the head water passage 40 and a cooling water circulation route for supplying the cooling water to the bore-surrounding water passage 50 are provided independently.

The cooling apparatus according to the modified example includes a first pump 63, a first radiator 64, a second pump 65, and a second radiator 66.

The first and second pumps 63 and 65 are activated by the rotation of the crank shaft (not shown) of the engine 10. The first and second pumps 63 and 65 are configured such that the discharging flow rate of the first pump 63 is larger than the discharging flow rate of the second pump 65 when a rotation speed of the crank shaft is constant, the first and second pumps 63 and 65.

The first and second radiators 64 and 66 are configured such that the degree of cooling the cooling water by the first radiator 64 is larger than the degree of the cooling the cooling water by the second radiator 66 when the flow rate of the cooling water flowing through the first radiator 64 is equal to the flow rate of the cooling water flowing through the second radiator 66.

One end 72A of the head water supply pipe 72 is connected to a discharging opening 63out of the first pump 63. The other end 72B of the head water supply pipe 72 is connected to the inlet 40in of the head water passage 40.

The outlet 40out of the head water passage 40 is connected to one end 74A of the head discharging pipe 74. The other end 74B of the head discharging pipe 74 is connected to an inlet 64in of the first radiator 64. An outlet 64out of the first radiator 64 is connected to one end 78A of a first return pipe 78 defining the cooling water passage. The other end 78B of the first return pipe 78 is connected to a suctioning opening 63in of the first pump 63.

The configurations of the communication water passages 41 to 46, the bore-side water passage 51, and the left and right between-bores water passages 52 and 53 are the same as the configuration of the communication water passage 41 to 46, the bore-side water passage 51, and the left and right between-bores water passages 52 and 53 of the embodiment, respectively.

A discharging opening 65out of the second pump 65 is connected to one end 73A of the block water supply pipe 73. The other end 73B of the block water supply pipe 73 is connected to the inlet 50in of the bore-surrounding water passage 50.

The outlet 50out of the bore-surrounding water passage 50 is connected to one end 75A of the block discharging pipe 75. The other end 75B of the block discharging pipe 75 is connected to an inlet 66in of the second radiator 66. An outlet 66out of the second radiator 66 is connected to one end 79A of the second return pipe 79 defining the cooling water passage. The other end 79B of the second return pipe 79 is connected to a suctioning opening 65in of the second pump 65.

According to the modified example, the degree of cooling the left between-bores portion 30L and the right between-bores portion 30R by the cooling water flowing through the left between-bores water passage 52 and the right between-bores water passage 53, is larger than the degree of cooling the bore-surrounding portion 30P by the cooling water flowing through the bore-surrounding water passage 50. Thus, the temperatures of the left between-bores portion 30L, the right between-bores portion 30R, and the bore-surrounding portion 30P may be maintained in the friction decreasing temperature range.

The cooling apparatuses according to the embodiment and the modified example, may be configured as shown in FIG. 10A. In the cooling apparatus shown in FIG. 10A, the inlet 50in of the bore-surrounding water passage 50 is connected to the other end 73B of the block water supply pipe 73 through a block connection water passage 501 provided in the cylinder head 20.

In particular, the block connection water passage 501 is provided such that one end of the block connection water passage 501 is open at a wall surface of the cylinder head 20 other than the block contact surface 20B, and the other end of the block connection water passage 501 is open at the block contact surface 20B. One end of the block connection water passage 501 is connected to the other end 73B of the block water supply pipe 73, and the other end of the block connection water passage 501 is connected to the inlet 50in of the bore-surrounding water passage 50.

Further, the cooling apparatuses according to the embodiment and the modified example, may be configured as shown in FIG. 10B. In the configuration shown in FIG. 10B, the inlet 40in of the head water passage 40 is connected to the other end 72B of the head water supply pipe 72 through a head connection water passage 401 provided in the cylinder block 30.

In particular, the head connection water passage 401 is provided such that one end of the head connection water passage 401 is open at a wall surface of the cylinder block 30 other than the head contact surface 30H, and the other end of the head connection water passage 401 is open at the head contact surface 30H. One end of the head connection water passage 401 is connected to the other end 72B of the head water supply pipe 72, and the other end of the head connection water passage 401 is connected to the inlet 40in of the head water passage 40.

Furthermore, the cooling apparatuses according to the embodiment and the modified example, may be configured as shown in FIG. 11A. In the configuration shown in FIG. 11A, the outlet 50out of the bore-surrounding water passage 50 is connected to one end 75A of the block discharging pipe 75 through a block connection water passage 502 provided in the cylinder head 20.

In particular, the block connection water passage 502 is provided such that one end of the block connection water passage 502 is open at the block contact surface 20B of the cylinder head 20, and the other end of the block connection water passage 502 is open at a wall surface of the cylinder head 20 other than the block contact surface 20B. One end of the block connection water passage 502 is connected to the outlet 50out of the bore-surrounding water passage 50, and the other end of the block connection water passage 502 is connected to one end 75A of the block discharging pipe 75.

Further, the cooling apparatuses according to the embodiment and the modified example, may be configured as shown in FIG. 11B. In the configuration shown in FIG. 11B, the outlet 40out of the head water passage 40 is connected to one end 74A of the head discharging pipe 74 through a head connection water passage 402 provided in the cylinder block 30.

In particular, the head connection water passage 402 is provided such that one end of the head connection water passage 402 is open at the head contact surface 30H of the cylinder block 30, and the other end of the head connection water passage 402 is open at a wall surface of the cylinder block 30 other than the head contact surface 30H. One end of the head connection water passage 402 is connected to the outlet 40out of the head water passage 40, and the other end of the head connection water passage 402 is connected to one end 74A of the head discharging pipe 74.

Furthermore, the cooling apparatus according to the embodiment, may be configured as shown in FIG. 12A. In the configuration shown in FIG. 12A, a common connection water passage 81 is provided in the cylinder head 20. The outlet 40out of the head water passage 40 is connected to one end of the common connection water passage 81. The outlet 50out of the bore-surrounding water passage 50 is connected to one end of the common connection water passage 81 through a block connection water passage 503 provided in the cylinder head 20. The other end of the common connection water passage 81 is connected to one end 76A of the common discharging pipe 76.

Further, the cooling apparatus according to the embodiment, may be configured as shown in FIG. 12B. In the configuration shown in FIG. 12B, a common connection water passage 82 is provided in the cylinder block 30. The outlet 50out of the bore-surrounding water passage 50 is connected to one end of the common connection water passage 82. The outlet 40out of the head water passage 40 is connected to one end of the common connection water passage 82 through a head connection water passage 403 provided in the cylinder block 30. The other end of the common connection water passage 82 is connected to one end 76A of the common discharging pipe 76.

Furthermore, the cooling apparatuses according to the embodiment and the modified example, may be configured as shown in FIG. 13A. In the configuration shown in FIG. 13A, introduction water passages 471 to 474 are provided in the cylinder head 20. One end of the introduction water passage 471 is connected to a between-bores supply pipe 83 defining the cooling water passage. The other end of the introduction water passage 471 is connected to the communication water passage 41. One end of the introduction water passage 472 is connected to the communication water passage 42. The other end of the introduction water passage 472 is connected to the communication water passage 43. One end of the introduction water passage 473 is connected to the communication water passage 44. The other end of the introduction water passage 473 is connected to the communication water passage 45. One end of the introduction water passage 474 is connected to the communication water passage 46. The other end of the introduction water passage 474 is connected to a between-bores discharging pipe 84 defining the cooling water passage.

The between-bores supply pipe 83 is connected to the head water supply pipe 72, and the between-bores discharge pipe 84 is connected to the head discharging pipe 74.

When the flow rate control valve 62 is provided in the block water supply pipe 73, the between-bores supply pipe 83 may be connected to the block water supply pipe 73 upstream of the flow rate control valve 62. Further, the between-bores discharge pipe 84 may be connected to the block discharging pipe 75.

Further, the cooling water circulation route for supplying the cooling water to the bore-side water passage 51, the left between-bores water passage 52, and the right between-bores water passage 53, may be provided such that the cooling water circulation route is separated from the cooling water circulation route for supplying the cooling water to the head water passage 40 and the cooling water circulation route for supplying the cooling water to the bore-surrounding water passage 50.

Furthermore, the cooling apparatuses according to the embodiment and the modified example, may be configured as shown in FIG. 13B. In the configuration shown in FIG. 13B, introduction water passages 541 to 544 are provided in the cylinder block 30. One end of the introduction water passage 541 is connected to a between-bores supply pipe 85 defining the cooling water passage. The other end of the introduction water passage 541 is connected to the bore-side water passage 51. One end of the introduction water passage 542 is connected to the bore-side water passage 51. The other end of the introduction water passage 542 is connected to the left between-bores water passage 52. One end of the introduction water passage 543 is connected to the left between-bores water passage 52. The other end of the introduction water passage 543 is connected to the right between-bores water passage 53. One end of the introduction water passage 544 is connected to the right between-bores water passage 53. The other end of the introduction water passage 544 is connected to a between-bores discharging pipe 86 defining the cooling water passage.

The between-bores supply pipe 85 is connected to the head water supply pipe 72, and the between-bores discharging pipe 86 is connected to the head discharging pipe 74.

When the flow rate control valve 62 is provided in the block water supply pipe 73, the between-bores supply pipe 85 may be connected to the block water supply pipe 73 upstream of the flow rate control valve 62. Further, the between-bores discharging pipe 86 may be connected to the block discharging pipe 75.

Further, the cooling water circulation route for supplying the cooling water to the bore-side water passage 51, the left between-bores water passage 52, and the right between-bores water passage 53, may be provided such that the cooling water circulation route is separated from the cooling water circulation route for supplying the cooling water to the head water passage 40 and the cooling water circulation route for supplying the cooling water to the bore-surrounding water passage 50.

Furthermore, the cooling apparatus according to the embodiment, may include radiators provided in the head water supply pipe 72 and the block water supply pipe 73, respectively in place of the radiator 61. In this case, the radiator provided in the head water supply pipe 72 is configured to decrease the temperature of the cooling water to a temperature capable of maintaining the temperature of the cylinder head 20 in the knocking prevention temperature range and the temperatures of the left between-bores portion 30L and the right between-bores portion 30R in the friction decreasing temperature range. In addition, the radiator provided in the block water supply pipe 73 is configured to decrease the temperature of the cooling water to a temperature capable of maintaining the temperature of the bore-surrounding portion 30P in the friction decreasing temperature range. In this case, the flow rate control valve 62 may be omitted.

Further, the cooling apparatus according to the embodiment, may include pumps provided in the head water supply pipe 72 and the block water supply pipe 73, respectively in place of the pump 60. In this case, the pump provided in the head water supply pipe 72 is configured to supply to the head water passage 40, the cooling water having the flow rate capable of maintaining the temperature of the cylinder head 20 in the knocking prevention temperature range and the temperatures of the left between-bores portion 30L and the right between-bores portion 30R in the friction decreasing temperature range. In addition, the pump provided in the block water supply pipe 73 is configured to supply to the bore-surrounding water passage 50, the cooling water having the flow rate capable of maintaining the temperature of the bore-surrounding portion 30P in the friction decreasing temperature range. In this case, the flow rate control valve 62 may be omitted.

Furthermore, the pump 60 may be an electric pump activated by electric power supplied from a battery and the like. When the pump 60 is the electric pump, the flow rate of the cooling water discharged from the pump 60 may be controlled, independently of the engine speed NE.

When the pump 60 is the electric pump, the pump 60 is electrically connected to the ECU 90. The ECU 90 sets a target of the opening degree of the flow rate control valve 62 and a target of the flow rate of the cooling water discharged from the pump 60 on the basis of the engine load KL, the engine speed NE, the head water temperature THWhd, the block water temperature THWbr and the like.

In particular, the ECU 90 sets the target of the opening degree of the flow rate control valve 62 and the target of the flow rate of the cooling water discharged from the pump 60 for supplying to the head water passage 40, the cooling water having the flow rate capable of maintaining the temperature of the cylinder head 20 in the knocking prevention temperature range and the temperatures of the left between-bores portion 30L and the right between-bores portion 30R in the friction decreasing temperature range, and supplying to the bore-surrounding water passage 50, the cooling water having the flow rate capable of maintaining the temperature of the bore-surrounding portion 30P in the friction decreasing temperature range. The ECU 90 controls the opening degree of the flow rate control valve 62 and the activation of the pump 60 such that the opening degree of the flow rate control valve 62 corresponds to the target thereof, and the flow rate of the cooling water discharged from the pump 60 corresponds to the target thereof. 

What is claimed is:
 1. A cooling apparatus of an internal combustion engine for cooling a cylinder block of the internal combustion engine and a cylinder head mounted on the cylinder block by cooling medium, comprising: a first passage formed in the cylinder block, through which the cooling medium flows for cooling between-bores portions each corresponding to a portion of the cylinder block surrounding and between adjacent cylinder bores formed in the cylinder block; a second passage formed in the cylinder block, through which the cooling medium flows for cooling a bore-surrounding portion corresponding to a portion of the cylinder block surrounding the cylinder bores other than the between-bores portions; and a cooling medium supplying mechanism for supplying the cooling medium to the first and second passages such that ability of the cooling medium for cooling the between-bore portions, is different from the ability of the cooling medium for cooling the bore-surrounding portion.
 2. The cooling apparatus according to claim 1, wherein the cooling medium supplying mechanism includes a head passage formed in the cylinder head, through which the cooling medium flows for cooling the cylinder head, and the first passage is connected to the head passage.
 3. The cooling apparatus according to claim 1, wherein the cooling medium supplying mechanism includes: a common passage communicated with the first and second passages; and a flow rate control valve for controlling a flow rate of the cooling medium supplied to the second passage via the common passage.
 4. The cooling apparatus according to claim 1, wherein the cooling medium supplying mechanism includes: a first cooling device for cooling the cooling medium supplied to the first passage; and a second cooling device for cooling the cooling medium supplied to the second passage, and ability of the first cooling device of cooling the cooling medium is larger than the ability of the second cooling device of cooling the cooling medium. 